New images of asteroid collision show impact ‘much bigger than expected’

The James Webb and Hubble telescopes on Thursday revealed their first images of a spacecraft colliding with an asteroid, as astronomers indicated that the impact appears to be much larger than expected.

Both pointed towards the Dimorph space rock earlier in the week. It was a historic test of self-defense capability against a potential asteroid that threatens Earth in the future.

Astronomers rejoiced when NASA’s Dart (Double Asteroid Redirection Test) hit the asteroid on Monday. Pyramid-sized and rugby-ball shaped, the target was 11 million kilometers from Earth.

Images recorded by ground-based telescopes showed a vast cloud of dust expanding out of Dimorpho and Didymus, another asteroid in its orbit, following the spacecraft’s impact.

While these photos showed matter being spread out over thousands of kilometers, James Webb and Hubble “zoom in much further,” said Alan Fitzsimmons, an astronomer at Queen’s University Belfast involved with Project Atlas, a near-Earth asteroid observation system.

James Webb and Hubble can offer a view “within just a few kilometers of the asteroids and you can clearly see how matter is flying out of the explosive impact of Dart,” Fitzsimmons told AFP.

“It’s really spectacular,” he says.

Another image taken by James Webb’s Near-Infrared Camera (NIRCam) four hours after the event showed “plumes of material appearing as wicks coming out of the center of where the impact took place”, according to a joint European Space Agency (ESA) statement. ).

Hubble images at 22 minutes, 5 and 8 hours after impact show the spray of expanding matter from the place where Dart hit.

‘Worried that there was nothing left’

Ian Carnelli of the European Space Agency said the “truly impressive” images from Webb and Hubble were remarkably similar to those taken by the LICIACube satellite. This third satellite was separated a few weeks ago from the Dart spacecraft and was just 50 kilometers from the asteroid.

The photographs depict an apparently “much larger than expected” impact, says Carnelli, director of ESA’s Hera mission, which aims to inspect the damage in four years.

“I was really worried that there was nothing left of Dimorfo” at first, Carnelli admitted to AFP.
The Hera mission, scheduled to launch in October 2024 and arrive at the asteroid in 2026, hopes to survey a crater approximately 10 meters in diameter.

Now it looks like it will be much bigger, said the director, “if there is a crater, maybe a part of the Dimorph has been cut out.”

The true measure of Dart’s success will be how much exactly it deviated from the asteroid’s trajectory. With this information, the world can begin to prepare for self-defense against larger asteroids, which could head towards Earth in the future.

It is likely that Earth-bound telescopes and radars will take at least a week for a first estimate of how much the asteroid’s orbit has changed. For an accurate measurement, Carnelli says the timeframe is three or four weeks.

big implications

“I’m expecting a much bigger deflection than we planned,” confesses Carnelli.

This would have “big implications for planetary defense, as it means this technique can be used for much larger asteroids,” he said.

“Until today, we thought that the only deflection technique would be to send a nuclear device.”

Fitzsimmons said that even if no matter had been “thrown out” of the Dimorph, Dart would still have slightly affected its orbit.

“But the more matter and the faster it is moving, the greater the deflection,” explains the astronomer.

The James Webb and Hubble observations will help reveal how much and how quickly matter bounced off the asteroid, as well as the nature of its surface.

The asteroid impact marked the first time the two space telescopes had observed the same celestial body.

Since launching in December and releasing its first images in July, James Webb has withdrawn the title of Hubble’s most powerful space telescope.

Fitzsimmons revealed that the images were “a beautiful demonstration of a complementary science that you can achieve using more than one telescope simultaneously”.